Soak the rice noodles in warm water until pliable, 8–10 minutes. Drain well.
Whisk broth, soy sauce, oyster sauce, fish sauce, lemon juice, sugar, pepper, and salt in a bowl.
Heat oil in a large wok over medium-high heat. Sear chicken until lightly browned, 4–5 minutes. Transfer out.
Sauté onion in the same wok until translucent, 2 minutes. Stir in garlic and cook 30 seconds.
Add carrots and celery. Stir-fry until crisp-tender, about 2 minutes.
Toss in cabbage and snow peas. Cook until just wilted, 1–2 minutes.
Return chicken to the wok. Pour in the sauce and bring to a lively simmer.
Add drained noodles. Toss constantly until noodles are tender and most liquid is absorbed, 3–5 minutes.
Fold in green onions. Adjust seasoning and serve hot.